Lightning arrester



G. F. GRAY.

LIGHTNING ARRESTER.

APPLICATION FILED JAN. 11, 1919.

1,407,061 Patented Feb. 21, 1922. I

3440a 'VVtOZ v ing the alinement of the rounded electrodes. with the surfaces of the spacing disc.

umrnn STATES GIDRGE FRANCIS GRAY, OF PITTSBURGH, PENNSYLVANIA.

LIGHTN IN G ESTER.

Specification of Letters Patent.

Patented Feb. 21, 1922.

Application filed January 11, 1919.. Serial No. 270,688.

To all whom it may concern:

Be it known that I, Gnonon FRANc sGRAY, a citizen of the United States, residing at Pittsbur h, in the county of Allegheny and State of ,ennsylvania, haveinvented certain new and useful Improvements in L1ghtm ng Arresters, of which the followlng 1s a specification.

My invention relates to improvements in lightning arresters, and it conslsts 1n the combinations, constructions and arrangements herein described and claimed.

An object of my invention is to providea li htning arrester of simple construction, which is easily assembled and cheap to manuiacture, for use principally on low voltage circuits, such as railway-slgnal, telephone, fire-alarm, tele raph, and similar lines.

A further object of my invention is to provide a lightning arrester of the vacuum type, whose electrodes may be readily spaced apart the proper distance for the most efficient working of the device.

A further object of my invention is to provide a lightning arrester which may have a relatively short spark gap without the danger of short circuits around the gap, owing to the p hrovisionof novel means for preventing suc short circultmg.

A further obj ect of my invention is to provide a lightning arrester having electrodes shaped to give a selective path which is most suitable for the exact gas pressure in the device.

Other objects and advantages will appear in the following specification, and the novel features of the invention will be particularly pointed-out in the appended claims.

My invention is illustrated in the accompanying drawing, forming part of this application, in which- Figure 1 is a sectional view showing half of the lightning arrester in perspective;

Figure 2 is a view showing the means for holding or mounting the device;

Figure 3 is a sectional view of a modified form of the device;

Figure 4 is a sectional view of a modified form of the spacing plate or disc;

Figure 5 is a plan view of another modified form of spacing disc; and

Figure 6 is a detailed sectional view show- In carrying out my invention, I provide two metal punchings A, B, respectively,

such as those shown in Figure 1. These punchings are similar in shape. Each is ,rim 3. Each of the members A and B carries an electrode embodied in a central electrode, portlon 4;, formed by spinning, or otherw1se fashioning the metal body portion. The tips of the electrodes are preferably rounded, and the inner hollow portions of the electrodes form sockets 5, by means of whlch the device may be held or mounted in a holder.

A circular spacing plate 6 is provided, this plate consisting of mica, or other suitable insulator, having a central opening 7. Its preferred construction is that shown more in detail in Figure 4. The cup-shaped electrode-bearing plates A and B, together with the spacing plate 6, are sealed in position along their edges with a suitable insulating varnish or compound 8, and then with a moulded material 9, such as bakelite, to give mechanical strength. Afterassembling the parts, the interior of the chamber thus formed 1s exhausted, and the opening 10, by means of which the air is exhausted, is sealed by soldering 11, or in any other suitable manner.

In use, the unit is mounted in a convenient holder, such, for instance, as that shown in F gure 2. In this figure, a base 12 is provlded with metal springs 13, held by binding posts 14, each of the springs having a curved portion 15, arranged to enter a portion of the socket 5, so as to hold the lightning arrester in position, and at the same time to provide an effective electrical connection.

A unit thus formed is of very simple construction, easily assembled, and cheap to manufacture. In use the unit serves to connect the circuit to be protected, as for in- Y stance the wire 17, to the earth, the llghtning shaped electrodes 20, having rounded ends 21, facing the opening 7, in the disc 6. In this form of the device, the ad ustment of the electrodes to the desired distance apart may be accomplished by pushing them 1nto the cup-shaped holders A and ll to the desired distance, the electrodes being arranged to frictionally engage the interior walls of the retainer so as to firmly hold them in position. For ordinary use 1t is preferable to have the rounded ends of the electrodes in alinement with the surfaces of the spacing disc 6.

In Figure 4;, I have shown a preferred form of plate for spacing the electrode retainers apart, which is especially desirable for use in providing high insulation resistance when the device is subjected to many heavy discharges. To this end the plate, which I have denoted in general by 6, 1:3 in fact, made up of a plurality of layers such as those shown at 6, 6 and 6, these layers having holes 6 and W of difierent diameter, so as to provide long leakage surfaces. This construction also has the additional function of preventing the condensation of metallic vapors. I have found by experience that metallic vapors, which condense on exposed surfaces, do not penetrate into deep, narrow recesses, and for th1s reason such construction provides additional insulation.

In the use of lightning arresters on railway signalling circuits, unusual precautions are required to prevent short circuitlng the gaps by the fusing of the electrodes wlth extra heavy discharges. In such case, tips of special metal, such as carbon, tungsten or special brass, may be attached to serve as arcing points, and in addition the spacing disc, instead of having one large, central opening, may be perforated with a number of small holes. In Figure 5, I have shown a spacing disc 6* which is provided with an area having small holes 24: through which the discharge may take place. These holes are so small, however, that they prevent any of the melted metal from short circuiting the two electrodes, since the drops of the melted metal would be too large to pass through the openings.

In order to provide for some variation in gas pressure, it is desirable to have the opposing electrodes somewhat rounded, as in Figure 1. It is well known that for any given gas, the product of the pressure times the gap is constant for minimum sparking voltage, and as the pressure varies, a suitable gap is provided by the spherically shaped electrodes.

1 claim:

1. In a lightning arrester, a pair of cupshaped members having their open ends facing each other and having electrodes, an insulating spacing plate disposed between the mower opposed e es of said cup shaped members, 66

and means or securing the parts in position.

2. In a lightning arrester, a pair of cup shaped electrode carrying members disposed with their rims facing toward one another, a perforated spacing plate disposed between the opposed edges, and insulating retaining means for securing the parts in position.

3. In a lightning arrester, a pair of con ducting cup-shaped electrode carrying members arranged to face one another, an insulating, er orated, spacing plate disposed between t e opposed edges of said cup-shaped members, and insulating plastic material for securing the edges of said plate and said members together.

4. In a lightning arrester, a pair of oppositely disposed, cup-shaped electrode carrying terminals having their open ends facing each other, an insulating plate disposed between the edges of said opposed terminals, and means for securing the edges of the plate and the terminals together and for insulating said terminals from one another.

5. In a lightning arrester, a pair of opposed cup-shaped conducting members, electrodes carried by said members and spaced apart to provide a spark gap, an insulating plate disposed between the edges of said members, means for securing the edges of the plate and the edges of the members together, said means also constituting an insulating means, and the space within the cupghaped holders constituting a vacuum chamt. In a lightning arrester, a pair of opposed metal, cup-shaped members having in- Wardly extending projections constituting electrodes, means including an insulating plate for spacing said opposed members apart, plastic means for holding said plate and said members in fixed relation and for insulating them, the space between the opposed plates constituting a vacuum chamber.

7. In a lightning arrester, a pair of opposed metal cup-shaped members having central, portions pressed inwardly toward one another and constituting electrodes, an insulating spacing plate provided with" an opening, said disc having its edges disposed between the edges of the cup-shaped members, insulating plastic material covering the contiguous edges of the plate and the cupshaped members for securing the parts in position and for insulating the cup-shaped members.

8. In a lightning arrester, a pair of opposed members, electrodes carried by said members, and an insulating spacing plate consisting of a series of insulatin having registering openings of a i erent SIZGS.

lateS.

its

9. In a lightning arrester, a pair of opmembers, and an insulating spacin plate having inwardly projecting electrodes and a disposed between the edges of said e ectrode medianly arranged perforated insulating 10 holders, said insulating plate having'a recess plate disposed between the rims of said cupof relatively narrow depth and relatively shapedmembers; and means retainin said 5 great diameter, and bemg provided with rims in rigid connection with each ot er to openin on each side of said recess. constitute a closed casin 10. n a lightning arrester, in combina- In testimon' whereof aflix m si ature.

tion, a pair of metal cup-shaped members G ORGE FRANOI G AY. 

